The present embodiments relate to a lamella collimator. In particular, the present embodiments relate to a beam therapy appliance, and to a beam therapy appliance with a lamella collimator.
A lamella collimator is used in radiation therapy for the treatment of tumors. DE 196 39 816 A1 and WO 00/46813 describe lamella collimators. During radiation therapy, a tumor is irradiated with high-energy beams, generally with high-energy X-ray radiation from a linear accelerator. The lamella collimator may be placed in the beam path of the X-ray beam. The lamella collimator includes a plurality of lamellae that can be displaced against each other by a motor to define an aperture with a contour corresponding to the contour of the tumor. Only the tumor is irradiated with the X-rays; not the adjacent healthy body tissue. Two sets of lamellae may be arranged in relation to each other in such a way that their end faces can be moved toward and away from each other. As a result, virtually any tumor contour may be modeled.
Each of these lamellae can be individually displaced by an electric motor. During the positioning of a lamella, there can be slight deviations between a desired value and the actual set position of the lamella. Each lamella includes a position measurement apparatus with which the actual position set can be determined.
Particularly narrow lamellae are used to model very fine contours. DE 196 39 861 A1 describes a lamella collimator with narrow lamellae. In addition, the lamellae of the lamella collimator are often arranged in a semicircular shape in the beam direction and slightly inclined toward each other. This is a reliable way of avoiding narrow gaps between the individual lamellae, which greatly reduce the shielding effect of the lamella collimator in this region and would result in the irradiation of healthy body tissue.
With the lamella collimator described in DE 196 39 861 A1, the individual lamellae are provided on their upper edges on the side facing way from the beam side with oblong connecting cords, the other end of which engage the cords of a position measurement apparatus, which is not shown, for example by ball connectors. For reasons of space, as seen from the direction of travel of the lamellae, the connecting cords spread out in a fan shape, like that in a mechanical typewriter.
The mechanical connection of the individual position measurement apparatuses to individual lamellae is very complicated.